The Stickney Water Reclamation Plant in Illinois is one of the largest wastewater-treatment facilities in the world, serving about 2.3 million people and cleaning an average of 700 million gallons of wastewater a day.
The world relies on transit to keep things moving. This includes metro systems, airplanes and airports, cruise ships, and car-rental companies. These transportation systems require cleaning and maintenance to remain reliable for the millions of passengers who use them each year.
From wading in the 9/11 Memorial pools in New York City to sanitizing the train cars of Tokyo's famous metro system, we've traveled the world to take a look behind the scenes at experts who are responsible for some of the most intricate deep cleanings. Watch all the cleanings in this 2023 "Deep Cleaned" marathon.